Most solid rocket motors or boosters utilize O-rings in their construction and assembly, with large diameter O-rings sealing the segment clevis joints and nozzle flange against hot exhaust gases being most critical. In general, these joints are sealed by a combination of a pair of O-rings and heat-resistant putty over an interior region of the joints. O-rings used in these joints are constructed of an elastic, resilient material and are packed into grooves circumferentially located in the clevis joint and nozzle flange during booster assembly.
Primary concerns about these O-rings is their inability to maintain elasticity at depressed temperatures and a tendency to burn or deteriorate when exposed to hot exhaust gases. This was graphically illustrated on Jan. 28, 1986, when the Space Shuttle Challenger was destroyed as a result of an O-ring failure due to loss of elasticity brought on by unusually cold weather. Other disadvantages of O-rings include uncertain sealing under transient pressures upon ignition and the possibility of damaging the O-ring during stacking, or assembly, of the booster segments. Testing of the O-rings after the booster is assembled is limited to applying pressures to a point between the O-rings to observe the pressure at which the O-rings become unseated.
Accordingly, it is an object of this invention to provide a clevis joint and nozzle flange seal which is insensitive to a wide range of temperatures, consists of a solid metal ring that seals by twisting, and locks under pressure of booster ignition yet unlocks readily during disassembly. This seal is designed to be easily retrofitted to replace O-rings and to have an operating temperature range from the cryogenic to the very hot.